Air or gas cleaning apparatus



Feb. 22, 1955 T. w. CARRAWAY AIR OR GAS CLEANING APPARATUS 3 Sheets-Sheet 1 Filed NOV. 19, 1952 INVENTOR Tfiomaa iffcarran j BY 2mm, 944 M ATTORNEYS Feb. 22, 1955 T. w. CARRAWAY AIR OR GAS CLEANING APPARATUS 3 Sheets-Sheet 2 Filed Nov. 19, 1952 INVENTOR m 0.772 a WCa Wren a $14, r Jim-44 V ATTORNEYS MDQW Feb. 22, 1955 T. w. CARRAWAY AIR OR GAS CLEANING APPARATUS 3 Sheets-Sheet 3 Filed Nov. 19, 1952 INVENTUR 'Hama C Wra s a3 BY vv QM v Q, Y

AHURXH'S United States Patent AIR 0R GAS CLEANING APPARATUS Thomas W. Caraway, Dallas, Tex. Application November 19, 1952, Serial N0- 321,478

11 Chilli- (CL 261-27) This invention relates to air or gas cleaning apparatus, and comprises improvements upon the appara tus of the type described. and claimed in my prior Umted States Patents Nos. 2,539,344 and 2,583,252.

A feature of the instant structure is the PI'OVlSlOIl of supervisory parts controlling the movement of power devices serving to deliver a washing liquid, for distributing this liquid to a cleaning or dust removal chamber, and for moving the-air or gas through such chamber, with timing devices for procuring a proper order of operation ofsaid power devices during the starting period and during the shut-down period.

Another feature of the invention is the provision of such supervisory control apparatus eflEective for mamtaining liquid in a reservoir at a predetermined mimmum level, for successively operating liquid delivering and d18- tributing elements and serially thereafter an air or gas moving element, during the starting period; and effective during the shutdown period for successively terminating the delivery of liquid from the reservoir while maintaining a delivery of fresh liquid, of maintaining the air or gas moving element in operation for a time adequate to purge the air or gas ducts and then stopping the same, and thereafter stopping the operation of the liquid distributing elements and the fresh liquid supply and restoring the system to idle condition ready for re-starttng, while permitting the automatic'supply of make-up llqllld while in idle condition.

A further feature of the invention is the prov1sion of such a supervisory control system in association with means for sectionalizing the air or gas ducts leading from a plurality of points, under control of the system whereby the sectionalization is made effective automatically upon failure of liquid or manually when a point is not in service in order that dangerous, e. g. explosive, comnents in the moving air or gas may not be brought rate the cleaning system when the same is unable to remove the said components and may occasion an explosion or other damaging effect therein and therefrom.

With these and other features as'objects in view, an illustrative form of the apparatus is shown on the accompanying drawings, in which:

Fig. 1 is a conventionalized showing of a building equipped with apparatus and embodying the invention,

with the building and parts of the apparatus being shown in vertical section and other parts of the apparatus in el vation;

Fig. 2 is an enlarged vertical section on a larger scale and showing a part of the cleaning chamber;

Fig. 3 is a detail view of a check-valve for controlling the movement of liquid;

Fig. 4 is a similar detail view of another check-valve for a like purpose;

Fig. 5 is a detail view of a solenoid-operated valve.

for controlling fluid flow, with the solenoid structure in conventionalized section;

Fig. 6 is a fragmentary view in perspective, with parts broken away, showing a system-controlling float and two switches operated thereby;

Fig. 7 is a wiring diagram.

The illustrative embodiment of the invention is shown as being installed in a building including a floor 1 and walls 2 and 3 which define a work room 4 and apparatus room 5. A table 6 located in the work room 4 may be used for doing work which may result in dust or solid Earticles (such as trinitrotoluene, flour or grain dust, etc.)

2,702,695 Patented Feb. 22, sss

ice

order to eliminate danger of moved from the atmosphere. I

The form of apparatus shown includes air mtakehoods of which one hood 7 is illustrated, the hoods being located at a suitable level above work tables of which the table 6 is illustrated, and communicating with an air intake duct 8 which leads to the bottom of a cleaning or dust .removal chamber 9. Preferably the duct 8 is so connected to the chamber 9 that the air or gas enters the chamber 9 tangentially.

Closely related to and preferably supported on the top of the chamber 9 is a blower 10 driven by an operating motor 11 for moving air through the chamber 9 and discharging it through a duct 12. If desired, another intake duct 13 maybe arranged to draw in from an upper level in the room 4 and deliver it to the cleaning chamber 9 by way of the main intake duct 8 in proportion determined by setting of a damper 14. Illustratively,

a further duct 13a is shown as leading from another point for delivering air to the main intake duct 8 under .control of a damper 14a.

Because the air or gas shaft 15, and a plurality of vertically spaced impellers mmg entrained in the atmosphere and which, in

16 rotatable with the shaft 15. The upper end of the hollow shaft 15 is closed (Fig. 2) and is supported by a bearing 17a carried by a spider 17b in the chamber 9. The bottom shaft bearing 17 is constructed and sealed in any suitable manner to permit the flow of cleaning fluid up through the hollow shaft from a recirculation pipe 18 fed with fluid under pressure by a pump 19 driven by an operating motor 20. Fresh or non-recirculated washing fluid may be delivered from a fresh liquid supply pipe S to the pipe 18 and into the hollow shaft 15 under the control of a normally closed solenoid-operated valve 22 for a purpose to be described later.

A check valve 23 in the pipe line 18 permits the flow of recirculated fluid from the pump to the shaft '15 but not reversely, and a check valve 24 in the pipe 21 permits the flow offresh cleaning fluid from the valve 22 to the shaft 15, but not'reversely. The check valve 23 is detailed in Fig. 3, with its movable valve element 23* shown opened for upward movement of recirculated fluid from the pump 19: when this pump-induced flow ceases, the element 23" drops and prevents the reverse flow. The check valve 24 is detailed in Fig. 4 as having the control element 24 in the opened position in which makeup liquid from the supply pipe S may move therethrough when the solenoid valve 22 is opened: if liquid supply through pipe S fails, the check valve 24 closes to prevent flow of liquid back toward the supply line S, regardless 1 the closing element 22 which can be raised to flow-permittmg position when the solenoid coil 61 is energized by current flowing through the conductors 117,118: and a spring 22 is illustratively provided for closing the valving element 22 when such current flow ceases.

In order to prevent entrained droplets of water or cleaning liquid from entering the blower 10 and being carried out through the discharge duct 12, one or more filters 25 comprising matted minute glass or the like strands or fibres may be mounted in the upper end of the chamber 9. I

The impellers 16 may vary as to their specific construction, but preferably are so arranged that they communicate with the interior of the shaft 15, so that fluid delivered under pressure within the shaft will be sprayed out into the chamber 9 when the shaft and impellers are stationary, and will be thrown centrifugally outwardly when the shaft and impellers are rotating. The impellers may be constructed, for example, as shown in Patent No. 2,539,344, referred to above.

The electric motor 40 for driving the hollow impeller explosion, should be re- V enters the bottom of the clean-' ing chamber 9 tangentially, it will swirl spirally as it is 3. shaft has a pulley 41 on its shaft for moving thebelt 42 coiligected with the pulley 43 fixed on the hollow The larger particles of cleaning fluid. will impinge upon the filters 25 and the Walls of the chamber 9, and will drain .into a collecting basin 26 at the bottom of the chamber. For economical reasons it is desirable to reuse the cleaning fluid, but before reuse the collected dust and solid particles should be removed from the fluid. In the illustrative embodiment of the invention, the used cleaning fluid collected in the basin 26 flows downwardly through a return pipe 27 and is delivered to a suitable separating equipment such as a decanter 28 shown in Figure l, and serving also as a reservoir. includes three chambers29, 30, and 31 and downwardly extending baflles 32. The fluid moves quietly from right to left from one chamber into the next, permitting the dust or solid particles to precipitateand collect n the bottoms of the chambers in a well known manners Fluid which has passed the baflie 32 at the left hand chamber 31 encounters a screen 33 at the end of an intake pipe connection 34 leading to the pump 19.

In the normal operation of the equipment thus far described the pump 19, the impellers '16, and the blower 10 will run continuously. Recirculated fluid from which the chamber '9 and for delivering fresh cleaning fluid to the chamber for a predetermined period prior to stopping of the blower 10 and the impellers 16. Thus, when the system is to be put out of operation the pump stops,

- thereby discontinuing the delivery of recirculated clean- The decanter equipment most of the dust and solid particles have been separated by the decanter 28 will be forced by the pump 19 through the pipe 18 and hollow shaft 15, and thence outwardly through the rotating impellers 16-for intimate contact with the air or gas swirling upwardly through the chamber 9. The dust and solid particles in the air or gas will I adhere-to the moisture particles which, upon impinging on the filters or the walls of the chamber 9 will drain to the collecting basin 26, and then be returned through the pipe 27 to the decanter 28 for recleaning.

Some moisture will evaporate in the chamber 9, and some few particles of unevaporated moisture may be carried past the 'filters 25 and discharged through the duct 12. In order to replenish the supply of cleaning fluid in the recirculation system the valve 22 is opened from time to time to permit fresh cleaning fluid to flow into the hollow shaft 15 and out through the impellers 16. The opening and closing of the valve 22 for main of the equipment when the fluid level in the reservoir 28 taining a proper fluid level in the decanter or reservoir 28 isgzfontrolled automatically by means to be described herein er.

Means is provided for assuring the timing of the starting and stopping of the pump 19, the blower 10 and the inflow of fresh uncirculated cleaning fluid,,all at the proper times so as to avoid the presence of dry dust particles in the chamber 9, in the dis- .charge duct 12 or adjacent the blower 10 while this blower is operating. When the blower 10 and pump 19 are stopped after the system has been in operation for some time, the walls of the chamber 9, the filters 25, and the shaft 15 and impellers 16 will be covered with cleaning fluid. If the last cleaning fluid to flow into the chamber 9 was recirculated by the pump 19 it might contain some residuum of dust or solid particles, not separated from fluid in the decanter 28. If the system should remain out of operation for some time the moisture within the chamber 9 would evaporate, leavin a de sit of dust articles within the chamber 9, on e sh 15 and the pellers 16. Certain kinds of dust, for example, that including TNI particles, have such tremendously explosive potentialities that there would be danger of an explosion occurring if the chamber 9 and the shaft and impellers were not thoroughly wetted before the impellers and the blower shaft start to run when the system is put in operation again. To eliminate this danger, means are provided, effective during a stopping period, for rinsing the walls of chamber 9, collector 26, and return pipe 27 with fresh-liquid,whereby to rinse and purge these parts before the apparatus comes to a standstill. Further, means are provided for automatically and serially initiatin operation of the impeller shaft 15 and the pump 19, and ereafter the blower 10 after the lapse of a predetermined period following an initial delivery of cleaning fluid to the chamber 9. Thus, when the apparatus comes to a-standstill, the chamber 9 and associated parts are freed fromthe possibility of dry powdery particles or.

the impellers 16, anding fluid, and simultaneously the fresh water control valve 22 opens automatically, causing fresh water to be delivered by the impellers to all parts within the chamber 9. "Ihe'blower and impeller shaft continue to run and fresh wateris delivered for a predetermined period at the close of whichthe blower stops. During a further predetermined period, the impeller shaft continues to run and fresh-water is further delivered to assure .the rinsing after the flow of air or gas has stop shaft comes to a standstill, and the valve 22 is closed unless a further delivery of fresh water is then demanded for bringing the liquid level in the reservoir'28 to the desired point. The use of the fresh water exclusively, without any recirculated water, during the last part of the blower operation reduces to an absolute minimum the amount of dust which may remain in the chamber 9 after the fluid evaporates.

I The control mechanism preferably also includes means such as a float controlled valve responsive to lowering of the cleaning fluid to a predetermined level in the decanter Y valve 22 and maintaining it open until the desired level in the reservoir 28 is restored. The control mechanism also preferably includes a safety device which disables all falls to another predetermined level somewhat lower than that which causes opening of the make-up valve 22.

The equipment for controlling the adding of replacement fluid to the system or stopping of the system may include a float switch assembly 62 of the kind disclosed and claimed in my Patent No. 2,539,344; As shown in Figure 6, this equipment includes a casing 63 which may conveniently be mounted on the reservoir 28. A shaft 64, journaled for rocking movements in the casing 63, is formed with a radial arm 65 connected to a depending link 66 extending through a fixed guide 67 for connection to a float 68. Fast on the shaft 64 is' a cam 69 adapted, upon lowering of the fluid level in the reservoir 28, to close a normally open micro-switch 112 so as to energize the sole- I noid 61 and open the valve 22. Also fast on the shaft 64 is a cam 71 which normally maintains a micro-switch 108 closed. When the float 68 descends to a predeter-" mined level, lower than that at which the switch 112 is closed. the cam 71 is moved to such a position as to open the switch 108, thereby stopping operation of the entire system in a manner to be described later.

The supervisory system will now be described as to structure and operatiomin connection with the diagram in Fig. 7 which illustratively shows electrical elements and connections for the purpose.

, The general construction and arrangement of the parts described above is similar to the construction and arrangement disclosed in Patents Nos. 2,539,344 and 2,583,252, previously referred to. In accordance with the present invention, the blower 10 is so operated or controlled that it is delayed in starting, which follows only after the shaft '15 and, impellers 16 have been in operation for a period suflicient to wet and wash the interior walls of the chamber 9 and the parts contained in the chamber. In the form shown in the drawings, the delayed or retarded starting of the blower is procured by control electrical circuits and elements including a timing device which after a predetermined, preferably adjustable time interval,

etfects closure of the power circuit to the-blower motor 11. Such circuits and elements of the illustrative form will now be described.

The motors 11, 20, 40 are illustratively shown as of three-phase type, and the supply mains correspondingly have three conductors leading to the main or cut-ofl switch 101, from which the conductors 102 extend to the magnetic motor switches 103, 104, 105 and 106 which determine the operation of the several motors.

begun, together with the preparation of the atmosphere 85 So long as there is a predetermined minimum quantity ped: and then the impeller of liquid in the reservoir 28, the float-operated safety supervisory switch 108 remains closed, so that current from one of the conductors 102 may flow through the branch 109, the switch 108 and energize the supervisory conductor 110, under general control of the main switch 101. When less than the desired level of liquid is present it the reservoir 28, automatic replenishment normally occurs as long as main switch 101 remains closed; but when the level in the reservoir falls below this minimum, that is, when there is not a suflicient supply of liquid for safe operation (e. g. if the main liquid supply pipe S fails, and there is no make-up of losses), the switch 108 opens, and the system comes to a standstill regardless of the position of main switch 101. When the supply pipe S is ready to deliver make-up liquid, and the reservoir level is low, the float-controlled make-up control switch 112 is closed, and current flows from the supervisory conductor 110 by branch 113 'and by conductor 116 to switch 112, and thence by conductor 117 to the coil 61 of the solenoid valve 22, with return by a common return conductor 118 to a conductor 102 of proper phase. The valve 22 opens, and make-up liquid flows from supply pipe S to pipe 21 and through the check valve 24 to the hollow impeller shaft 15; direct flow. to the reservoir 28 being prevented by the check valve 23. The liquid passes through the impellers 16 into the chamber 9, descends therein, and passes by pipe 27 to the decanter: when the desired maximum level is attained, the float again opens the switch 112, and therewith deenergizes the coil 61 so that the make-up valve 22 closes again.

Concurrently with opening of the valve 22 upon enertion of conductor 117,. current also flows through the ranch 117 thereof to the coil 120 of the motor switch 103, with return by conductor 118' to the common return conductor 118. Relay 103 is closed, and current flows from conductors 102 to the impeller motor 40, and the impellers 16 on shaft 15 are rotated so long as the floatoperated switch 112 remains closed.

A first control relay 115 is associated with a first preferably adjustable time delay device 132 which acts during the starting cycle to impose a time delay of, e. g. two minutes, upon the movement of relay 115 so that the chamber 9 is thoroughly wetted before the blower 10 is started; and which acts during the shutting-down cycle to maintgin the blower in operation until the ducts are purge To place the system in full operation, an operation switch 122 is moved upward in the diagram (Fig. 7), opening one set of contacts and closing two sets of contacts.

Current can now flow from the supervisory conductor 110 by conductor 113 to conductor 116 and thence by branch 116*, now-closed upper contacts of the operation switch 122, conductor 124 to the respective coils 125, 126 of the motor switches 104, 105, with return by the conductor 102 connected to the common return conductor of the first control relay 115 closes contacts so that conductor 116 is connected to conductor 142 leading to the coil 143 of the blower control switch 106 and thence to the common return conductor 118. The switch 106 closes, and the blower motor 11 runs.

The system is now in full operation. The motors 11, 20, 40 are driving the blower, pump and impellers. The rotation of motor 40 is independent of the open or closed position of the switch 103. If the reservoir 28 becomes filled to the desired maximum, the float-controlled switch 112 opens and deenergizes conductor 117: the switch 103 opens without etfect on the motor 40; the solenoid 61 is deenergized, and the supply of make-up liquid is cut off. When the liquid level falls, switch 112 closes, and the solenoid 61 is energized again to'procure delivery of makeup liquid.

When the system is to be shut down, the operation sw tch 122 is moved downward in the diagram (Fig. 7). Switch 122 opens the circuit through conductor 116 to conductor 124, so that the coils 125, 126 of the motor switches 104, 105 are deenergized and theseswitches open.v The pump motor 20 and the pump 19 stop at once: the control of the impeller motor 40 is transferred from motor switch 105 to motor switch 103. The switch 122 also opens the circuit to conductor 128 so that the first time delay device 132 begins to count a time interval prior to re-opening, illustratively here the heater is deenergized so that the contacts will open after a predetermined and preferably adjustable time interval. However, the first time-delay device 132 maintains the energization of coil 130 and thus of the first control relay 115.for this time c. g. 2 minutes, found competent to continue air or gas flow by blower 10 until the ducts are purged. Operation switch 122 also closes its lower contacts, and current flows from supervisory conductor 110 by branch 145 through the still-closed upper contacts of the first control relay 115, conductor 146, the normally closed lower contacts of the operation switch 122, conductor 147, coil 148 of the second control relay 140, and back to the common return conductor 118. The second control relay 140 moves,

and its contacts are closed for current flow from the supervisory conductor 110 by branch 150, closed contacts of relay 140, to conductor 117 and its branch 117', so that the coil 120 of magnetic motor switch 103 and the solenoid 61 of the supply valve 22 are energized regardless of the position of the float-controlled switch 112.

Current from conductor 147 also flows to the second time delay device 155 (likewise illustrated as a thermostatic device and having normally open contacts) and begins to initiate its timed closure, with return by conductor 118 to the common return conductor 118. The time .delay switch 155 closes e. g. at one minute after movement of switch 122, before the time delay relay 132 opens e. g. at two minutes; and closure of the device 155 establishes a holding circuit for relay 148 and therewith maintains energization of the solenoid 61 and the 118. The motor switches are energized and the motors I, 40 rotate and drive 'the pump 19 and the impellers 16. It will be noted that the energization of motor 40 through switch 105 is independent of the energization by switch 103; so that if the motor is already turning when switch 105 closes, the motor continues in motion even though switch 103 may be later opened consequent upon a filling of the reservoir 28 and opening of the float switch 112, and conversely the closure of switch 103 by float action, at a time when the switch 105 is being deenergized by opening the operation switch 122, will continue the motion of motor 40 until the reservoir has been refilled.

Movement of the operation switch 122 also closes contacts which connect the conductor 124 with a conductor 128 leading to the actuating part of a first time delay device 132 (conventionally illustrated as of thermal type with the actuating part being a heater, and with normally open but thermally closed contacts), and by conductor 118 back to the common return 118.

A tentative circuit also exists from the supervisory conductor 110, by branch 113 and the coil 130 of the relay 115 to one contact of the first time delay device 132: the other contact of said first delay device; being connected to conductor 118 and thus back to the common return 118. After the predetermined time interval for the first time delay device 132 (illustratively when the heater causes closure of the contacts at the end of two minutes), current flows through this tentative circuit, the

relay 103 so that liquid is supplied and the impeller driven even after relay re-opens the circuit to conductor 146. Opening of relay 115, however, deenergizes the relay coil 143, and stops the blower motor 11. When relay 115 opens, the cessation of current flow to conductors 146,

'147 also initiates a circuit-opening action of the second time delay device 155, e. g. de-energizing the illustrative heater, and after say one minute from the opening of relay 115 and thus three minutes after the movement of switch 122, the device 155 opens again and breaks the maintaining circuit through coil 148; the second control relay likewise opens, and the impeller motor 40 and the solenoid valve 61 are returned to the control of the float switch 112.

Thus, during the shutting down period initiated by the movement of operation switch, the pump 19 is stopped at once; the blower motor 11 continues to run for a time adequate to purge the air or gas ducts, and then stops; the impellers 16 continue to operate during a time interval after the blower stops, to insure a rinsing of the chamber 9 and its discharge pipe; and the solenoid valve 22 remains open during the shut-down period so that fresh liquid is being employed for the rinsing, rather than the possibly dirtier liquid from the reservoir 28.

The time delay devices 132, serve to close contacts a first predetermined time interval after the respective switch is energizd and to open the contacts a second predetermined time interval after a further control action:

coil 130 is energized and the relay 115 moves. Movement 85 illustratively they are conventionalized as thermostatically actuated devices, commercially available, in which contact-closure occurs at the first time interval after the heater is de-energized.

A control for the dampers 14, 14" is also provided, as shown in Figs. 1 and 7. The high voltage supply acting through the safety level switch 108 to charge the conductor 110 is connected to a voltage-reducing transformer 190 for charging the conductors 191, 192.

Switches 193, 193* can be closed selectively and manually, so that when the conductor 110 is charged, control current flows by the respective conductors 194, 194 to the respective coils 195, 195 which operate the biased dampers 14, 14 to open the same; with return by conductor 192. When the water level in the reservoir 28 drops to the minimum safe level for operation, current flow to conductor 110 ceases, and therewith that to coils 195, 195", so that the dampers close, and the'main hood 7 over the point at which the greatest danger exists receives the full eflect of the draft while blower 10 is coming to a standstill. As soon as the conductor 110 is re-charged, the dampers open and ventilation begins again. If ventilation through ducts 13 or 13'- is not needed, the respective switches 193, 193* may be opened; and then the draft is exerted upon the hood 7 and upon the yet-open ducts 13, 13'.

It will be apparent that apparatus or systems embodying the invention are capable of efficiently removing dust and-solid particles from air or gas during continued operation with a minimum danger of explosions occurring within the apparatus itself. The concept of providing independent and preferablyadjustable timing means for controlling the starting and stopping of the several motors and the fresh fluid supply valve, and the apparatus and controls for putting these concepts into operating effect results in important advantages and safeguards.

Although the apparatus disclosed embodies the invention in the form now preferred, it will be apparent that changes may be made in the arrangement of parts, and other physical forms of individual parts may be employed without departing from the invention. Thus it may be desirable in some installations to employ other than three-phase equipment, and in certain instances it may be to advantage to provide transformer equipment for placing the control circuits and relays under low voltage operation. It is intended that the scope of the invention be determined by the appended claims rather than by the specific disclosure of a preferred embodiment.

I claim:

1. In apparatus for removing dust or solid particles from gas, a removal chamber having a liquid collecting basin at its bottom; a blower for moving gas contaminated with such particles through the chamber, driving means for operating the blower; a liquid diflusing impeller mounted to rotate in said chamber, driving means for operating the impeller; means for supplying liquid to said impeller including a pump and means for driving the pump whereby the particles are moistened in the chamber and collected thereby in said basin; and power supplying means connected to said driving means for the impeller and pump and including a connection to said blower driving means, a timing device placed in operation to measure a timing interval upon initiation of movement of the impeller and pump, and means controlled by the timing device eifective at the end of the timing interval -to control said blower connection and start the blower after the chamber walls have been moistened.

2. In apparatus for removing dust or solid particles from gas, a removal chamber having a liquid collecting basin at its bottom; a blower for moving gas contaminated with such particles through the chamber, a liquid difiusing impeller mounted to rotate in said chamber, a pump for supplying liquid to the impeller whereby the particles are moistened in the chamber and collected thereby in said basin; separate electric motors for driving said blower, said impeller, and said pump; electric circuit means for supplying current to said electric motors and control circuit means including an operation switch connected for procuring immediate energization of said impeller and pump motors upon closure of said operation switch, a time delay device, and means connecting said operation switch, time delay device and the blower. motor for procuring energization-of the blower motor at a 'predetermined time interval after closure of said operation switch and after the chamber walls have been moistened. 3. In apparatus for removing dust or solid particles from gas, a removal chamber, a blower for moving gas through the chamber, a fluid diffusing impeller mounted to rotate in said chamber, a pump for supplying fluid to the mpeller, separate electric motors for driving said blower, said impeller, and said pump; electric circuit meansfonsupplying current to said electric motors and including independent electrically actuated switches for said motors, a circuit breaker, a timing device effective for controlling the closure of the circuit breaker, an operation switch connected for directly energizing and closing the said independent switches for the impeller and pump motors, and a connection from said operation switch controlled by said timing device and circuit breaker for procuring the closing of the blower motor switch at a predetermined time interval after closure 0 the operation switch.

4. In apparatus for removing dust or solid particles from gas, a removal chamber, a blower for moving gas through the chamber, a fluid diffusing impeller mounted blower, said impeller, and said pump; electric circuit t means for supplying current to said electric motors, a fluid supply line and valve, and control circuit means in-. cluding an operation switch connected for procuring im-. mediate de-energization of the pump motor upon openmg of the operation switch, a first time delay device con-. nected to the operation switch and to the blower motor. for procuring a continued action of the blower for a predetermined time interval after the opening of the operation switch, and a second time delay device connected to the operation switch, the impeller motor and the valve for procuring a continued action of the impeller, and delivery of fresh fluid for a predetermined time after stoppage of the blower.

5. In apparatus for removing dust or solid particles from gas, a removal chamber, a blower for moving the gas through the chamber, a pump for supplying recirculating fluid to the chamber for contacting and washingthe gas moving therethrough, independent electric motors for driving the blower and the pump, current supplying switches for said motors, means for supplying fresh fluid to the chamber independently of the pump including an electrically actuated valve, an operationswitch and control circuit means connecting said switches and including timing devices for procuring the starting of the blower motor at a predetermined time after the operation switch is moved to starting position, for deenergizingthe pump motor and for opening said electrically actuated valve immediately upon movement of the operation switch to stopping position, formaintaining the blower motor energized for a predetermined time after such movement of said latter switch and thereupon deenergizing the same, and for reclosingssaid valve a predetermined time interval after the blower, motor has been de-energized.

6. An apparatus as in claim 5 including an impeller in said chamber, an independent electric motor for driving the impeller, and circuit connections under control of thetiming devices for starting the impeller motor when the starting-stopping switch is moved to starting position and for maintaining the energization of the impeller motor until the valve is closed.

7. In apparatus for removing dust or solid particles from gas, a removal chamber, a blower for moving gas through the chamber, a fluid difiusing impeller mounted to rotate in said chamber, a pump for supplying fluid to the impeller, separate electric motors for driving said blower, said impeller, and said pump; electric circuit means for supplying current to said electric motors and including independent electrically actuated switches for said motors, a first control relay, a first time delay device, an operation switch, and circuits controlled by said relay, device and operation switch, including a first conductor from the operation switch for procuring closure of the. pump and impeller switches immediately upon closure of the operation switch, a second conductor from the opera-- tion switch for energizing the first time delay device upon closure of the operation switch, a third conductor including the coil of the first control relay and contacts in the first time delay device for procuring closure of the first control relay upon timed closure in the first time delay device, and a fourth conductor from a contact of the first control relay for procuring closure of the blower motor switch at a time interval determined by said first time delay device after closure of said operation switc 8. In apparatus for removing dust or solid particles from gas, a removal chamber, a blower for moving gas through the chamber, a fluid diffusing impeller mounted to rotate in said chamber, a pump for supplying fluid to the impeller, separate electric motors for driving said blower, said impeller, and said pump; electric circuit means for supplying current to said electric motors and including independent electrically actuated switches for said motors, a first control relay, a first time delay device, a second control relay, a second time delay device, an operation switch; and circuits controlled by said relays, devices and operation switch, including a first conductor from the operation switch for holding the pump motor switch closed while the operation switch is closed and for opening the same immediately when the operation switch is opened, a second conductor from the operation switch for holding the first time delay device closed while the operation switch is closed, a third conductor including the coil of the first control relay and contacts of the first time delay device for maintaining the first control relay closed for a time interval after opening of the operation switch, said operation switch having normally closed contacts, a fourth conductor including normally open contacts of the first control relay and normally closed contacts of the operation switch and connected to the coil of the second control relay and to the second time delay device for energizing the same, a fifth conductor including contacts of the second time delay device and connected with the coil of the second control relay for maintaining'the same energized for a predetermined time interval after opening of the first control relay, and circuits connecting said relays and motor switches for procuring operation of the blower motor for a predetermined time after opening of the operation switch and for maintaining operation of the impeller motor during and for a predetermined time after the stoppage of said blower motor. s

9. An apparatus as in claim 8, including a fresh fluid supply and valve, an electrical actuator for the valve, and connection from said second control relay to the said actuator for opening said valve upon opening of the operation switch and to close the valve concurrently with the stoppage of the, impeller motor.

10. In apparatus for removing dust or solid particles from gas originating at a plurality of points, independent ducts leading from the said points; a removal chamber connected to said ducts; a blower for moving gas through the chamber, driving means for operating the blower; a fluid diffusing impeller mounted to rotate in said chamber, driving means for operating the impeller; means for supplying fluid to the impeller including a pump, and means for driving the pump; and power supplying means connected to said driving means for the impeller and pump and including a connection to said blower driving means, a reservoir connected to receive fluid from the chamber and deliver the same to the pump, means responsive to the fluid level in the reservoir and connected for interrupting the power supply to said driving means when the said fluid level is below a minimum, independent dampers in said ducts, and connections from said fluid level responsive means for procuring closure of the dampers when the fluid level falls below said minimum.

11. In apparatus for removing dust or solid particles from gas, a removal chamber; a blower for moving gas through the chamber, driving means for operating the blower; a fluid diffusing impeller mounted to rotate in said chamber, driving means for operating the impeller; means for supplying fluid to said impeller including a pump and means for driving the pump; and power supplying means connected to said driving means for the impeller and pump and including a connection to said blower driving means, a timing device placed in operation to measure a timing interval upon interruption of said power connection to the blower, and.means controlled by the timing device efiective at the end of the time interval to stop the pump and impeller whereby moistening of particles in said chamber continues after stoppage of the blower.

References Cited in the file of this patent UNITED STATES PATENTS Feinbcrg Feb. 26, 1952 

